For a variety of reasons: no boss nobody telling you what to do able to take time off from work when you want However, being self employed is not the "free ride" that it may seem ... it takes lots...
Just apply for the job that your looking to get into and then they'll call if your application/resume looks good.
If that occupation is licensed in your state, and it is in most(all?) states, it would be up to the state licensing agency.
Are you kidding? I was self employed at age 14, mowing lawns.
Legal age to contract is 18.